ICs

The RE46C180 is a low power, CMOS
ionization-type, smoke detector IC. With minimal external
components, this circuit will provide all the required
features for an ionization-type smoke detector.
An on-chip oscillator strobes power to the smoke
detection circuitry for 5 ms every 10 seconds to keep
the standby current to a minimum.
A check for a Low Battery condition is performed every
80s and an ionization chamber test is performed once
every 320s when in Standby. The temporal horn pattern
complies with the National Fire Protection Association
NFPA 72 ®
National Fire Alarm and Signaling Code® for
emergency evacuation signals.
An interconnect pin allows multiple detectors to be connected,
such that when one unit alarms, all units will
sound. A charge dump feature quickly discharges the
interconnect line when exiting a Local Alarm condition.
The interconnect input is also digitally filtered.
An internal 9 minute or 80s timer can be used for a
Reduced Sensitivity mode.
An alarm memory feature allows the user to determine
whether the unit has previously entered a Local Alarm
condition.
Utilizing low-power CMOS technology, the RE46C180
is designed for use in smoke detectors that comply with
the Standard for Single and Multiple Station Smoke
Alarms, UL217 and the Standard for Smoke Detectors
for Fire Alarm Systems, UL268.